掺Bi石英光纤的γ射线辐照和温度影响特性

采用改进的化学气相沉积法制备了尺寸为10/130 μm的掺Bi单包层石英光纤, 把光纤分成若干组之后置于不同剂量的⁶⁰Co γ辐射源下辐照, 测试了光纤在辐照前后的吸收谱和荧光谱, 并测试了光纤在全温度范围(-40–70 ℃)下荧光强度的变化. 实验结果表明, 辐照后700, 800 nm处的吸收峰显著增强, 这是由于辐照导致更多Bi 近红外活性中心的生成. 976 nm光抽运不同剂量辐照后的光纤, 中心位于1230 nm的荧光谱没有明显变化, 验证了掺Bi石英光纤用于太空及辐照环境下光通信的可能性. 在全温度范围内, 分析了荧光强度的变化规律, 为今后掺Bi光纤激光器的稳定工作提供了数据基础.

Irradiation and temperature influence on the Bi-doped silica fiber

We report Bi-doped fibers prepared by modified chemical vapor deposition combination with solution doping process. The fibers are divided into three groups under ⁶⁰Co γ radiations with different doses. The absorption spectra and fluorescence spectra of the fiber before and after irradiation are investigated. The dependence of fluorescence intensity of the fiber on temperature (-40-70 ℃) are measured. Experimental results show that the radiation-induced absorptions (RIAs) of the fibers increase significantly at 700 nm and 800 nm with the increase of the irradiation dose. We ascribe the great enhancement of the RIA of the fiber to the generation of more Bi near-infrared (NIR) active centers. Because near infrared nonluminous valance state like Bi³⁺ captures free electrons and converts into Bi²⁺, and further into Bi⁺under the ⁶⁰Co γ radiations with different doses. We also find that the NIR fluorescence spectra are stable before and after irradiation under 976 nm LD excitation. The possibility of communication in a radiation environment is proved, such as in outer space is proved. In addition, the fluorescence intensity dependence on temperature in a full-temperature range is analyzed, and we find that the fluorescence intensity decreases with the increase of temperature. It is contributed to the Bi active center that Bi⁺ may gradually turn into nonluminous Bi metallic colloids during thermal activation. The variation law of fluorescence intensity is analyzed in the whole range of temperature. We believe that the variation law of fluorescence intensity provides data and basis for the stable operation of bismuth-doped fiber laser in the future.